Fuel supply system



1966 H. E. VARVEL. 33 9 FUEL SUPPLY SYSTEM Original Filed May 24, 1.961

#1 INVENTOR M92040 :7 t/me'mz ATTORNEY United States Patent 7 Claims.(Cl. 158--36.3)

The present application is a continuation of applicants prior co-pendingapplication Serial No. 112,344, filed May 24, 1961, now abandoned.

This invention relates to a filter unit and, more particularly, to theimproved fuel supply system which it enables for portable space heatersand like equipment.

A primary objective in constructing a space heater is to embodysuificient controls to insure safety in its use. For example, a spaceheater normally requires a fuel which, if not entirely consumed in aburning process, will leave dangerous and objectionable fumes in itscombustion chamber. It has proven extremely difficult to avoid theoccurrence of such fumes. However, the present invention does providecontrols, the use of which obviates this problem. Moreover, in so doingit does in fact provide not only a safer but also a more efficient andeffective space heater.

To further illustrate the problems which the invention solves, it mustbe understood that in the space heater of the prior art its fuel supplyline normally incorporates a filter in its lower end which depends inand adjacent to the bottomof its fuel tank. In drawing fuel from thetank, under suction or pressure, the fuel passes through the filter fromadjacent its bottom and upwardly through the fuel supply line toeventually pass to and from a burner head to a combustion chamber. Thehead normally provides a mixing or siphon type nozzle for mixing airwith fuel and delivery thereof for ignition in the combustion chamber.

In the operation of such a space heater it has been found that when theheater has been left running and the level of fuel in the supply tankfalls below the filter, rather than fuel flow terminating, a capillaryattraction takes place between the filter and the fuel. This capillaryaction results in an intermittent pulsating flow of fuel from the bottomof the tank, under the influence of applied suction, for example. As aresult, fuel is delivered to the burner in small amounts and in spurts,causing the burner unit to sputter and spit raw fuel into the combustionchamber. This not only creates dangerous fumes but results in incompletecombustion and leaves a dangerous combustible residue in the combustionchamber.

It has also been found to be a characteristic of prior art space heatersthat when a heater is turned off with the level of fuel anywhere abovethe bottom of the fuel tank, fuel nevertheless still remains in thenozzle. This fuel eventually issues to the combustion chamber in liquidor fume form, leaving, in this instance also, dangerous fumes andresidue. Moreover, using the prior art fuel supply systems and filters,the filters have a strong tendency to clog. This also interferes withproper fuel flow and produces, in the space heater, poor and incompletecombustion.

All of the above noted problems are obviated in the practice of theinvention.

A preferred embodiment of the present invention enables a fuel supplysystem for space heaters and like equipment wherein the inherentlyvented fuel supply tank has its delivery opening bridged by a filterelement, preferably of powdered metal or its equivalent. In conjunctiontherewith, a shield-like tubular housing is engaged about the filter toextend from the delivery opening of the tank and to depend and form anextended hollow chamber therebelow, in advance of the filter. It will beseen that this unit as applied in the fuel supply system of a spaceheater or similar equipment produces a novel function and significantlyimproved safety control features.

A primary object of the invention is to provide a novel fuel filter unitfor a particularly advantageous incorporation in a fuel tank, which unitmay be economically fabricated, more efficient and satisfactory in use,adaptable to a wide variety of applications and unlikely to createmalfunctions in the fuel systems in which it is incorporated.

Another object of the invention is to provide a fuel filter unitparticularly applicable to effect improvements in heating systemsinvolving the supply of liquid combustibles.

A further object of the invention is to provide a novel filter unitapplicable to the vented fuel supply tank of a space heater or likeequipment to produce a fuel supply system which renders the space heatersafer and more efiicient in operation.

An additional object of the invention is to provide a novel filter unit,the proper application of which to the fuel supply tank of a spaceheater or the like will produce an automatic and complete cut-off of thefuel delivery therefrom on the fuel reaching a predetermined level inthe tank.

Another object of the invention is to incorporate an improved filterunit in the supply system of a space heater or like equipment to producethereby a substantial elimination of the possibility of any dangerousaccumulation of fumes or combustible residue occurring in the combustionchamber of the space heater.

An additional object of the invention is to provide a space heater, suchas one using a conventional siphontype nozzle in its fuel supply system,with a filter so incorporated in its fuel supply line that on break ofsuction in the line a reverse flow of fuel takes place which inherentlypurges the nozzle and filter.

A further object of the invention is to provide in a space heater orlike equipment a filter unit applied to the fuel delivery lineinterconnectedin its fuel supply tank in a manner that enables it tooperate to effectively purge the line and interrupt the operation of theheater when the fuel supply in the tank reaches a dangerously low level.

A further object of the invention is to provide a fuel filter unitpossessing the advantageous structural features, the inherentmeritorious characteristics and the mode of operation herein mentioned.

With the above and other incidental objects in view as will more fullyappear in the specification, the invention intended to be protected byLetters Patent consists of the features of construction, the parts andcombinations thereof, and the mode of operation as hereinafter describedor illustrated in the accompanying rawings, or their equivalents.

Referring to the accompanying drawing wherein is shown one but obviouslynot necessarily the only form of embodiment of the invention,

FIG. 1 is a cross-sectional view of a fuel supply tank embodying afilter unit in accordance with the invention; and

FIG. 2 is a schematic showing of the application of the apparatus ofFIG. 1 in a fuel supply system for a space heater, only so much of theheater apparatus being indicated as is necessary for the presentdisclosure.

Like parts are indicated by similar characters of reference throughoutthe several views.

Referring to the drawings, the invention unit is shown to include afilter element 1 of powdered metal or material or equivalentcharacteristic. This element is appro- 3 priately disposed to bridge thedelivery opening from a fuel tank 8. The tank 8, being a fuel tank, isshown as conventionally vented, the vent being illustrated asincorporated in the cap for the tank filler opening.

The element 1 has a generally cylindrical configuration including aradially projected flange 3 at one end 4. The latter is shown in FIG. 1of the drawings in a position external to the fuel tank proper. A cavity5 is provided in the uppermost surface of the element 1, the cavityextending axially and substantially the length of the filter.

The filter unit is completed by a tubular housing 2. The housing 2 hasan internal diameter greater than the external diameter of the filterelement 1. As seen in FIG. 1, the body of the element 1 depends in theupper end of the housing in concentric spaced relation to its inner walland has its flange 3 seated over such upper end and appropriately fixedthereto. The housing 2 has such an orientation and length to define anextended hollow chamber 6 below the filter 1.

In the embodiment illustrated the filter unit is fixed to dependvertically through the delivery opening in the fuel supply tank 8. Asshown, the dependent extremity 9 of the housing 2 positions in adjacentspaced relation to the bottom of the tank. The uppermost end of thefilter unit including the flange 3 is suitably seated in one end of acoupling 10, the flange 3 being positioned in abutment with a shoulder11. The coupling 10 is of a tubular nature, the shoulder 11 beingdefined by a counterbore in its end most adjacent the fuel tank 8.Accordingly, the shoulder 11 rims a delivery passage 12 adapted tocommunicate this filter cavity 5 with a fuel supply line interconnectedwith the coupling 10.

The coupling 10 is externally threaded to one end to screw into themeans defining the delivery opening in the tank 8 while its other end isreduced in external dimension and adapted for threaded engagement in theone end of the fuel supply line 13, the connection being schematicallyillustrated in FIG. 2 of the accompanying drawings. As seen in FIGURE 2the fuel supply system of the invention provides that the line 13 isconnected with a burner 14 through a suction means 15. The means 15 isconventionally operable to apply suction through the filter 1 to thefuel in the tank 8. As may be further observed in FIG. 2, the burner isarranged to discharge, in a conventional manner, such as through asiphon type nozzle, the fuel drawn from the tank 8 to a combustionchamber 17 within the housing 18 of a space heater 19. The burner will,of course, also be provided with suitable ignition means.

In the operation of the space heater 19 utilizing the filter unit of theinvention in the manner as illustrated, the suction means 15 isenergized to apply suction to the fuel in the tank 8 through the filterelement 1 and housing 2. This produces a vacuum condition in the chamber6 inducing a column of fuel within the chamber to flow upwardly to andthrough the fiter 1 to the cavity 5 and therefrom to the line 13 by wayof the delivery passage 12. The dependent extremity 9 of the housing 2is, as illustrated, adjacent and spaced from the bottom of the tank.Therefore, as long as the fuel level in the tank is at or above theextremity 9 fuel will continue to pass upwardly through the chamber 6,line 13, burner 14 and be discharged from the burner into the combustionchamber 17 by way of a conventionally included nozzle. This flow of fuelwill be smooth, even and continuous until the fuel level in the tankfalls below the extremity 9 of the housing 2. The instant this happens,due to the fact the chamber is naturally vented, air enters the chamber6 and there is a break in the existing vacuum. The end result of this isan immediate and automatic termination of the delivery of fuel to andfrom the burner 14.

It has been difficult to determine precisely what happens. However, ithas been found that once air enters the chamber 6 and the vacuum isbroken, there is fuel still in the upper portion of the housing 2, thefilter and the supply line. The interruption of the vacuum causes thisfuel to be drawn or to drop back through the filter 5, in the process ofwhich it inherently purges the filter of all fuel and, in fact, theadjacent fuel supply line. The purged fuel falls the length of thechamber 6 and into the bottom of the fuel tank.

The entrance and existence of air which has occured in the chamber 6prevents the occurrence of a capillary type of attraction by the filter1 for the fuel remaining in the tank as would normally occur were thefilter 1 not substantially displaced from the fuel by the extendedlength of the chamber 6. Thus the filter remains dry and there is ablock between the filter and the fuel.

It has been found that the break in the vacuum, as described, not onlyautomatically terminates the delivery of fuel to the burner 14- butthere no longer occurs any residual sputtering or spitting of raw fuelinto the chamber 17. The net effect of this automatic cut-off is toeliminate the possibility of any dangerous residue being left in thespace heater which could result in toxic fumes or a potentiallyexplosive substance.

Thus the function of the invention as above described is highlyimportant for adding safety and efficiency to the operation of spaceheaters and like equipment. Moreover, it may be readily seen therefromthat the invention filter may be equally advantageous in other similarappligations involving the transmission of potentially dangerous uids.

It should be noted that with the provision for the extended chamber 6through the medium of the housing 2 and the purging operation that takesplace in respect to the filter 1 when the level of fuel falls below theend 9 of the housing 2 the filter will not clog as would normally be thecase if the filter were positioned in a conventional manner adjacent thebottom of the tank. This also means that further fuel may be introducedinto the tank 8 and the filter will not interfere with a most effectiveoperation of the fuel delivery system as illustrated in reference to thespace heater.

The same safety conditions as above described would exist when a heateris cut off at any time when the fuel level in the tank is below thefilter.

It should be recognized that while filters may have previously been usedin the discharge opening from a sealed container of water or likesubstance to prevent undesirable foreign objects from passing from acontainer, no one heretofore has contemplated the use of a filter of acharacter described or in connection with a vented fuel tank in thesupply system of a space heater as illustrated with the attendantsignificant results.

From the above description it will be apparent that there is thusprovided a device of the character described possessing the particularfeatures of advantage before enumerated as desirable, but whichobviously is susceptible of modification in its form, proportions,detail construction and arrangement of parts without departing from theprinciple involved or sacrificing any of its advantages.

While in order to comply with the statute the invention has beendescribed in language more or less specific as to structural features,it is to be understood that the invention is not limited to the specificfeatures shown, but that the means and construction herein disclosedcomprise b-ut one of several modes of putting the invention into effect,and the invention is therefore claimed in any of its forms ormodifications within the legitimate and valid scope of the appendedclaims.

Having thus described my invention, I claim:

1. In combination with a burner head of a space heater or like equipmenthaving means in connection therewith for delivery thereto of fuel underthe influence of suction means and therefrom to an attached combustionchamber, a fuel tank having a delivery opening at its top, adapter meansin connection with said tank opening providing a delivery passagetherefrom and means for interconnection thereof with a supply lineleading to said head and communicated with the aforementioned suctionmeans, a filter fixed to said adapter to bridge said opening and todepend interiorly of said tank, said filter providing a cavity in freeand unrestricted communication with said delivery passage, a tubularhousing confined in said tank to depend vertically thereof to a pointadjacent its bottom, the uppermost end of said tubular housing beingbridged by said filter, the latter disposing in the path of fuel movingupward of said housing from adjacent the bottom of said tank under theinfluence of said suction means, said tubular housing forming anextended empty chamber in advance of said filter which, on level of fuelin said tank falling below said housing, receives air from said tank tobreak the vacuum produced by the suction on said housing, the result ofwhich is to induce the fuel uppermost of said chamber to be drawn downin a reverse flow to the bottom of said tank, the effect of which is topositively clear the line in said filter and thereby produce a sharp andautomatic interruption of the operation of said heater and inhibitafterflow.

2. In combination with a space heater including a burner head having afuel supply line in connection therewith and means incorporated to drawfuel through said line under the influence of suction, a fuel supplysystem for connection with said line consisting of a fuel tank havingmeans defining a delivery opening connected to said supply line, avertical tube dependent from said opening substantially to the bottom ofsaid tank, an elongated filter unit a portion of which covers the top ofsaid tube and is confined thereto by said means defining a deliveryopening and another portion of which smaller than said tube depends intothe tank in the top portion of said tube, said tube depending beyond thelower end of said filter unit and forming an extended empty chamber ofsubstantial volume and generally uniform cross-sectional dimensiontherebelow, the application of suction to said supply line producing alift of fuel to exit from said tank through said tube and filter in thetop portion of said tube, in the process of which a column of fuel isinherently maintained in said tube and the interconnected line, saidextended chamber, as defined, functioning immediately on break of thevacuum produced in said tube by said suction means to provide the fuelin the filter will drop therefrom in a manner to purge said filter andthereby preclude the further discharge to said burner head of raw fuel.

3. In combination with a space heater including a burner head having asiphon nozzle, a fuel storage tank, a delivery line from said tank tosaid nozzle, said tank having a delivery opening in the upper partthereof, said delivery line being arranged in absence of suction todrain fuel from said nozzle back to said tank, a vertical tube confinedwithin said tank to depend from said delivery opening adjacent to thebottom of said tank, the lower end of said tube being normally below thefuel level in said tank, the opposite ends of said tube being open, anda filter extending into the upper part of said tube having a cavity infree and open communication with said delivery line through saiddelivery opening and defining a chamber therebelow and means forcreating a suction in said delivery line to draw fuel from said tankthrough said tube and said delivery line to said nozzle, discontinuanceof said means allowing fuel in said delivery line and at said nozzle todrop back into said tank to and through said filter with resultantpurging effect.

4. A fuel storage tank according to claim 3, characterized by meansinstalled in the upper part of said tank having a through openingtherein defining said delivery opening, said means being disposed toalign said opening with the cavity in said filter as a continuationthereof, said opening being of a size freely to interconnect said cavityand said delivery line.

5. In combination with a space heater, a fuel storage tank connected forfluid communication with said heater and having a delivery opening inits upper end, suction means in said fluid connection, closure meansinstalled in said delivery opening and having a flow path therethroughhaving a diameter for a free and unrestricted withdrawal of fuel fromthe tank and draining thereof back to the tank, a vertical tubeprojecting downwardly from said closure means into the tank, theopposite ends of said tube being open, the upper end aligning with saidflow path, and an elongated filter element extending into said tank anddisposed lengthwise in said tube and having a head end secured in theupper end of said tube, said filter element having an axial cavityopening through the said head end, means locating said filter elementwith said head end at said closure means with said cavity in alignedunrestricted communication with said flow path, said filter elementhaving an opposite end projecting toward the lower end of said tube butspaced therefrom a distance to leave in said tube between the lower endthereof and the said opposite end of said filter a chamber of extendedlength.

6. A fuel storage tank according to claim 5, characterized in that saidmeans for locating said filter element includes a flange on said headend thereof overlying the upper end of said tube and held clampedthereto by said closure means.

7. In combination with a space heater including a burner head having asiphon nozzle, a fuel storage tank, a delivery line from said tank tosaid nozzle, said tank having a delivery opening in the upper partthere-of, said delivery line being arranged in absence of suction todrain fuel from said nozzle back to said tank, a vertical tube dependentwithin said tank from said delivery opening and extending to near thebottom of said tank, the lower end of said tube being normally below thefuel level in said tank, the opposite ends of said tube being open, and.a filter installed in the upper part of said tube having a cavity infree and open communication with said delivery line through saiddelivery opening and defining a chamber therebelow and means forcreating a suction in said delivery line to draw fuel from said tankthrough said tube and said delivery line to said nozzle, discontinuanceof said means allowing fuel in said delivery line and at said nozzle todrop back into said tank to and through said filter with resultantpurging effect, said filter being a cylindrical element having a headend interengaged with the upper end of said tube and a body portionextending into said tank in spaced concentric relation to said tube,said filter element terminating at its end opposite said head end withinthe tube a substantial distance from the lower end thereof to definewith the tube beneath the said opposite end of said filter element anopen space of substantial volume, said cavity being in said body portionand opening through said head end.

References Cited by the Examiner UNITED STATES PATENTS 703,654 7/1902Hall 2104l6 X 888,259 5/1908 Pauthonier 2104l6 X 1,352,671 9/1920 Maegly158-36.1 1,621,537 3/1927 Hardinge 15836 1,969,080 8/1934 Johnson15836.1 X 1,985,279 12/1934 Buller. 2,282,413 5/1942 Zoder 158-36.3 X2,421,329 5/1947 Hoffer.

FOREIGN PATENTS 480,832 7/1916 France.

REUBEN FRIEDMAN, Primary Examiner.

F. W. MEDLEY, Assistant Examiner.

7. IN COMBINATION WITH A SPACE HEATER INCLUDING A BURNER HEAD HAVING ASIPHON NOZZLE, A FUEL STORAGE TANK, A DELIVERY LINE FROM SAID TANK TOSAID NOZZLE, SAID TANK HAVING A DELIVERLY OPENING IN THE UPPER PARTTHEREOF, SAID DELIVERY LINE BEING ARRANGED IN ABSENCE OF SUCTION TODRAIN FUEL FROM SAID NOZZLE BACK TO SAID TANK, A VERTICAL TUBE DEPENDENTWITHIN SAID TANK FROM SAID DELIVERY OPENING AND EXTENDING TO NEAR THEBOTTOM OF SAID TANK, THE LOWER END OF SAID TUBE BEING NORMALLY BELOW THEFUEL LEVEL IN SAID TANK, THE OPPOSITE ENDS OF SAID TUBE BEING OPEN, ANDA FILTER INSTALLED IN THE UPPER PART OF SAID TUBE HAVING A CAVITY INFREE AND OPEN COMMUNICATION WITH SAID DELIVERY LINE THROUGH SAID DELIVRYOPENING AND DEFINING A CHAMBER THEREBELOW AND MEANS FOR CREATING ASUCTION IN SAID DELIVERY LINE TO DRAW FUEL FROM SAID TANK THORUGH SAIDTUBE AND SAID DELIVERY LINE TO SAID NOZZLE, DISCONTINUANCE OF SAID MEANSALLOWING FUEL IN SAID DELIVERY LINE AND AT SAID NOZZLE TO DROP BACK INTOSAID TANK TO AND THROUGH SAID FILTER WITH RESLULTANT PURGING EFFECT,SAID FILTER BEING A CYLINDRICAL ELEMENT HAVING A HEAD END INTERENGAGEDWITH THE UPPER END OF SAID TUBE AND BODY PORTION EXTENDING INTO SAIDTANK IN SPACED CONCENTRIC RELATION TO SAID TUBE, SAID FILTER ELEMENTTERMINATING AT ITS END OPPOSITE SAID HEAD END WITHIN THE TUBE ASUBSTANTIAL DISTANCE FROM THE LOWER END THEREOF TO DEFINE WITH THE TUBEBENEATH THE SAID OPPOSITE END OF SAID FILTER ELEMENT AN OPEN SPACE OFSUBSTANTIAL VOLUME, SAID CAVITY BEING IN SAID BODY PORTION AND OPENINGTHROUGH SAID HEAD END.